But i thought the way VanitySearch works is similar to bitcrack (sequentially) and not random. Doesn't that mean if 10 people start working on the same string you provided that they would all go through the same exact process and duplication?
It would be a huge security risk to have it run sequentially. It has a RNG to ensure the randomness.
Also on a separate note. For argument's sake lets say we run this for nearly 150 years and our grandsons get a match. Isn't there still a high possibility that since you defined only partial public key that the results would not be the exact same key? e.g. you've been waiting 100+ years for 1qwertyuiopBBBBBBOOOOO but your grandson gets 1qwertyuiopBBBBBZZZZZ instead?
Vanity gen brute forces using the given split public key. When it gets the correct solution, it'll produce your part public key and part private key. Give the private key combine with their part private key and the address will be as defined in the pattern.